PROJECT SUMMARY/ABSTRACT Despite notable increases in antiretroviral therapy (ART) adherence and decreases in mortality, South Africa is not close to achieving the UNAIDS goals of 90% of all people living with HIV (PLWH) diagnosed, 90% of those with a positive HIV diagnosis on antiretroviral therapy (ART), and 90% of those on ART with undetectable HIV RNA by 2020, with only 60% of all PLWH having undetectable RNA as of 2017. Moreover, in the Western Cape, the viral load suppression (VLS) rate (54.7%) is the second lowest in the country, and the average 6- month rate for retaining PLWH in primary health care clinics is 64%. Retention is critical for improving ART adherence and VLS. Clinics face myriad challenges retaining PLWH in care long enough to maintain VLS. Structural-, organizational-, and individual-level patient barriers impede retention. Nevertheless, a handful (about 8%) of health care clinics consistently have retention rates at 80% or above. Information about how these clinics manage to succeed despite pervasive barriers could help improve retention rates in clinics that are not performing as well. Positive Deviance (PD) is an approach to studying ways in which a minority of individuals or organizations succeed despite barriers that typically hinder success. The approach begins with a ?discover? phase in which intensive study is undertaken to uncover unique strategies of clinics with better outcomes than those facing similar challenges, followed by an implementation phase in which the strategies are implemented. In a collaboration among the RAND Corporation, the South African Human Science Research Council, and the South African Western Cape Department of Health, we propose (1) to use a PD approach and mixed methods research (a provider survey that assesses contextual factors thought to be associated with performance; patient shadowing; semi-structured interviews with clinic leaders, and focus groups with providers and patients) to discover strategies used by primary health care clinics that retain 80% or more of PLWH in care; (2) to develop an intervention that consists of a toolkit with novel PD strategies identified in Phase 1 and implementation science methods for successfully implementing strategies; and (3) to implement the PD intervention in 3 low-performing pilot clinics and conduct a pilot cluster randomized trial to evaluate (a) feasibility (extent to which the PD strategies are implemented); (b) acceptability (clinic staff attitudes about the toolkit, the strategies, and implementation processes); and (c) preliminary effects of the intervention on PLWH retention in care and VLS. To determine feasibility, we will collect attendance logs and activity worksheets; to assess acceptability, we will conduct focus groups with providers and patients; to assess preliminary effectiveness, we will examine changes in patient retention and VLS at intervention clinics from 6-months before the intervention and during the intervention period, compared to changes in all other low- performing clinics. The proposed study would be the first to experimentally test a PD intervention to improve retention in HIV care for PLWH; if effective, it could lead to higher retention and VLS rates and lower mortality.